Re: [PATCH net-next 1/2] vxlan: change vxlan_validate() to use netlink_ext_ack for error reporting

[Jiri Benc]

On Tue, 27 Jun 2017 22:47:57 +0200, Matthias Schiffer wrote:
>   if (!is_valid_ether_addr(nla_data(tb[IFLA_ADDRESS]))) {
> - pr_debug("invalid all zero ethernet address\n");
> + NL_SET_ERR_MSG_ATTR(extack, tb[IFLA_ADDRESS],
> + "invalid ethernet address");

Could we be more specific here? This is better than nothing but still
not as helpful to the user as it could be. What about something like
"the provided ethernet address is not unicast"?

> - if (mtu < ETH_MIN_MTU || mtu > ETH_MAX_MTU)
> + if (mtu < ETH_MIN_MTU || mtu > ETH_MAX_MTU) {
> + NL_SET_ERR_MSG_ATTR(extack, tb[IFLA_MTU],
> + "invalid MTU");

"MTU must be between 68 and 65535"

> - if (id >= VXLAN_N_VID)
> + if (id >= VXLAN_N_VID) {
> + NL_SET_ERR_MSG_ATTR(extack, data[IFLA_VXLAN_ID],
> + "invalid VXLAN ID");

"VXLAN ID must be lower than 16777216"

>   if (ntohs(p->high) < ntohs(p->low)) {
> - pr_debug("port range %u .. %u not valid\n",
> -  ntohs(p->low), ntohs(p->high));
> + NL_SET_ERR_MSG_ATTR(extack, data[IFLA_VXLAN_PORT_RANGE],
> + "port range not valid");

Since you're getting rid of the values output, I'd rather suggest more
explicit "the first value of the port range must not be higher than the
second value" or so. Shorter wording is welcome :-)

Thanks,

 Jiri

[PATCH net-next 1/2] vxlan: change vxlan_validate() to use netlink_ext_ack for error reporting

[Matthias Schiffer]

The kernel log is not where users expect error messages for netlink
requests; as we have extended acks now, we can replace pr_debug() with
NL_SET_ERR_MSG_ATTR().

While we're at it, also fix the !is_valid_ether_addr() error message (as it
not only rejects the all-zero address, but also multicast addresses), and
add messages for the remaining attributes.

Signed-off-by: Matthias Schiffer 
---
 drivers/net/vxlan.c | 20 ++--
 1 file changed, 14 insertions(+), 6 deletions(-)

diff --git a/drivers/net/vxlan.c b/drivers/net/vxlan.c
index fd0ff97e3d81..01957e39f2cd 100644
--- a/drivers/net/vxlan.c
+++ b/drivers/net/vxlan.c
@@ -2716,12 +2716,14 @@ static int vxlan_validate(struct nlattr *tb[], struct 
nlattr *data[],
 {
if (tb[IFLA_ADDRESS]) {
if (nla_len(tb[IFLA_ADDRESS]) != ETH_ALEN) {
-   pr_debug("invalid link address (not ethernet)\n");
+   NL_SET_ERR_MSG_ATTR(extack, tb[IFLA_ADDRESS],
+   "invalid link address (not 
ethernet)");
return -EINVAL;
}
 
if (!is_valid_ether_addr(nla_data(tb[IFLA_ADDRESS]))) {
-   pr_debug("invalid all zero ethernet address\n");
+   NL_SET_ERR_MSG_ATTR(extack, tb[IFLA_ADDRESS],
+   "invalid ethernet address");
return -EADDRNOTAVAIL;
}
}
@@ -2729,8 +2731,11 @@ static int vxlan_validate(struct nlattr *tb[], struct 
nlattr *data[],
if (tb[IFLA_MTU]) {
u32 mtu = nla_get_u32(tb[IFLA_MTU]);
 
-   if (mtu < ETH_MIN_MTU || mtu > ETH_MAX_MTU)
+   if (mtu < ETH_MIN_MTU || mtu > ETH_MAX_MTU) {
+   NL_SET_ERR_MSG_ATTR(extack, tb[IFLA_MTU],
+   "invalid MTU");
return -EINVAL;
+   }
}
 
if (!data)
@@ -2739,8 +2744,11 @@ static int vxlan_validate(struct nlattr *tb[], struct 
nlattr *data[],
if (data[IFLA_VXLAN_ID]) {
u32 id = nla_get_u32(data[IFLA_VXLAN_ID]);
 
-   if (id >= VXLAN_N_VID)
+   if (id >= VXLAN_N_VID) {
+   NL_SET_ERR_MSG_ATTR(extack, data[IFLA_VXLAN_ID],
+   "invalid VXLAN ID");
return -ERANGE;
+   }
}
 
if (data[IFLA_VXLAN_PORT_RANGE]) {
@@ -2748,8 +2756,8 @@ static int vxlan_validate(struct nlattr *tb[], struct 
nlattr *data[],
= nla_data(data[IFLA_VXLAN_PORT_RANGE]);
 
if (ntohs(p->high) < ntohs(p->low)) {
-   pr_debug("port range %u .. %u not valid\n",
-ntohs(p->low), ntohs(p->high));
+   NL_SET_ERR_MSG_ATTR(extack, data[IFLA_VXLAN_PORT_RANGE],
+   "port range not valid");
return -EINVAL;
}
}
-- 
2.13.2